The invention relates to a device for providing pipette tips.
Pipette tips are small tubes made of plastics material which serve for receiving samples of fluid, preferably in quantities of approximately 0.1 μl to 100 ml, in the laboratory. At the bottom they comprise a through-opening for fluid and at the top a through-opening for air, the cross section of the pipette tips generally increasing from the lower to the upper through-opening. For metering fluid, the upper end of the pipette tip is connected, for example, to a piston-operated pipette, so that the upper through-opening is attached to a device for displacing air from the pipette. To this end, the pipette tip with the through-opening is clamped onto an attachment of the pipette or clamped into a hole of the pipette. A channel opens into the front face of the attachment and/or into the bottom of the hole, said channel being connected to the displacement device of the pipette. By means of the displacement device, an air cushion is displaced so that a defined quantity of fluid is received into the pipette tip and is ejected therefrom. The metered quantity of fluid depends on the displacement of the displacement device. The pipettes may have uniform displacement, as fixed volume pipettes, or adjustable displacement, as variable pipettes. Moreover, the pipettes may be piston-operated pipettes or direct displacement pipettes. After use, the pipette tip is detached from its seat on the pipette, for which the pipette may comprise an ejector which upon actuation forces the pipette tip away from its seat. Afterwards, the pipette is able to receive a new pipette tip. Spillages of samples of fluid between successive meterings are thus avoided.
Filter pipette tips comprise a filter in the vicinity of their upper end which prevents aerosol or fluid from the pipette tip from entering into the pipette, and contaminating said pipette. Filter pipette tips generally have to be packaged in a sterile manner until used.
For attaching pipette tips to the seat of a pipette, pipette tips are provided on holders for pipette tips. Said holders comprise a perforated plate made of plastics, also called a “tray” or “wafer”, with a plurality of holes in a matrix arrangement. The perforated plate generally has 96 holes in 8 rows and with 12 slots. Pipette tips are inserted from the top into the holes, said pipette tips not falling through due to an upwardly widening diameter or a collar.
The perforated plate is, for example, connected integrally to a downwardly protruding peripheral frame which prevents inserted pipette tips from coming into contact with the support surface. Such a holder is described in DE 102 45 961 B4, the entire contents of which is incorporated herein by reference.
Moreover, holders for pipette tips exist in which perforated plates are able to be inserted releasably into a stackable frame. Such a holder for pipette tips is described in DE 197 42 493 C1, the entire contents of which is incorporated herein by reference.
Also known are holders for pipette tips which are configured as boxes or frames which are closed at the bottom. A perforated plate provided with pipette tips is able to be positioned on the upper edge of the holder, so that the pipette tips protrude into a receiver of the holder.
The pipette tips may be removed from a holder by pressing the seat of a single channel pipette or the seats of a multi-channel pipette from the top onto the upper ends of the pipette tips individually or a plurality thereof at the same time. In this case, considerable pressing forces may act, which the holder has to withstand so that the pipette tip is fixed sufficiently securely to its seat on the pipette. Accordingly, the holder or the sub-assembly consisting of the tray and holder have to be of stable configuration.
Holders in the form of boxes or frames are known which are discarded and/or reused after the removal of all pipette tips. The reusable holders are able to be filled by means of refill packs comprising fresh pipette tips. The refill packs may comprise a plurality of perforated plates which are filled with pipette tips. For example, refill packs are known in which one or more perforated plates filled with pipette tips are arranged in folding cardboard boxes or cardboard frames. Said refill packs are not sufficiently protected against contamination from dust, etc. Thus, it is not possible for sterile pipette tips to be made available.
In further known refill packs, a perforated plate filled with pipette tips is fastened releasably to the upper edge of the plastics container, the pipette tips protruding into the container. A further perforated plate is arranged thereover, the pipette tips thereof protruding into the pipette tips of the lower perforated plate, and which at the edge is releasably fastened to the lower perforated plate. Further plates with pipette tips are accordingly arranged thereover and the arrangement is covered from the top by a plastics cover which is releasably fastened to the uppermost perforated plate.
Refill packs of the type described above are disclosed, for example, in WO 92/01514 A1, U.S. Pat. No. 5,366,088 and U.S. Pat. No. 6,286,678 B1, the entire contents of each of which are incorporated herein by reference.
Embodiments of said refill packs are also known in which the lid is used for moving the perforated plates filled with pipette tips from the refill stack into the holder. The perforated plate is latched in the holder and the cover may be pulled off and to protect the opened refill pack from contamination is positioned onto the upper perforated plate of the refill stack.
Said refill packs have the drawback that they have to be opened for moving perforated plates with pipette tips held therein onto a holder. In this case, the pipette tips are at least partially accessible from the outside, so that they are not protected from contamination. In particular, when moved, the pipette tips may come into contact with the holder or other objects and as a result become contaminated.
The “Tip SystemBox” (product name from Sarstedt AG & Co, Nümbrecht, Germany) is a box with a folding lid made of autoclavable material into which, optionally for autoclaving, pipette tips are able to be inserted in a tray or in a stack consisting of trays filled with pipette tips (called “Tip StackPack”) in order to obtain a non-slip pipette position which is secure from tipping up. Optionally, there is the possibility of inserting so-called “Biosphere® Boxes” without contamination into the Tip SystemBox. The Biosphere® Boxes are stable boxes closed at the bottom which at the top carry a tray with pipette tips. A lid is positioned from the top onto the tray. In this application, the Tip SystemBox serves as a holder which is intended to prevent the downwardly tapering Biosphere® Box from tipping over when a pipette receives pipette tips. The stable Biosphere® Boxes are relatively costly disposable articles.
Sterile pipette tips have hitherto been generally handled in stable disposable boxes for processing and not in refill packs for moving into a box or frame. In contrast to reusable boxes, said disposable boxes are discarded after the removal of all pipette tips. The design thereof is costly in terms of material so that they are expensive to manufacture and produce waste packaging in large quantities for the user. Frequently, the components of said disposable boxes are not able to be dismantled easily enough. The user often compresses the remaining packaging in order to reduce the volume of waste. In this case, the conventional disposable boxes do not always permit the use of automated methods during manufacture.
The material consumption is correspondingly high for the packaging of sterile pipette tips and the quantity of waste produced during use.
Proceeding therefrom, the object of the invention is to provide a device for providing pipette tips which may be easily refilled, the risk of contamination of the pipette tips being reduced and the packaging waste being reduced. Moreover, the object of the invention is also to propose the use of a refill pack which permits easier refilling of pipette tips, the risk of contamination of the pipette tips being reduced and the packaging waste being reduced. Finally, the object of the invention is to provide a method for producing a refill pack which is suitable for use in a device according to the invention for providing pipette tips.